1. Field of the Invention
The present invention relates in general to the use of optical probes, and relates in particular to an elastic sock for containing and positioning a pulse oximetry probe.
2. Description of the Related Art
An optical probe generally operates by measuring a light signal passed through a medium. In oximetry, the optical probe attaches to an oximeter system such that the oximeter system determines at least one characteristic of the medium. In the medical field, a pulse oximetry probe measures a light signal passed through tissue. The light signal varies depending on, among other things, the oxygen saturation of the blood cells in the tissue. The oximeter system processes the measured light signals from the pulse oximetry probe and can determine characteristics of the tissue, including a pulse rate and blood oxygen saturation. The pulse oximetry probe is typically placed on an extremity, such as a finger, toe, hand, or foot of the person being monitored.
Today, pulse oximetry is a widely accepted and successful non-invasive technique for monitoring characteristics of patients. In addition, the conventional pulse oximeter probe is manufactured in a wide number of shapes and sizes. Generally, each shape and size typically employs adhesion-based, spring-tension-based, or hook-and-loop-based securing mechanisms to position and secure the optical probe to a measurement site.
However, the foregoing conventional securing mechanisms are often unworkable in certain environments. For example, adhesive-based securing mechanisms simply to not adhere to surfaces that are wet and/or fluid-covered, such as infant skin immediately following birth. For example, in the baby born at or near term, skin coatings such as vernix present adhesion problems, and in the preterm infant, adhesive-based sensors can harm the infant""s fragile skin. There are similar problems with the use of adhesive-based sensors during the treatment of burn victims.
Moreover, hook-and-loop-based securing mechanisms, such as Velcro straps, are often applied incorrectly. For example, the Velcro strap may be so loose that the optical probe falls off or that the optical probe emitter becomes misaligned from the optical probe detector during clinician-imposed or self agitation. On the other hand, the Velcro strap may be so tight that they may cause poor perfusion and sores. The foregoing drawbacks are especially apparent with newborns.
In addition to the forgoing infant concerns, environments including severely damaged and/or sensitive tissue, such as burns or the like, pose a number of problems for the conventional securing mechanisms. For example, adhesive-based securing mechanisms may affix itself to fragile newly healed skin such that removal of the adhesive causes the skin to tear, thereby redamaging the tissue and causing pain to the patient. Moreover, the Velcro-based securing mechanisms may again apply too little or too much pressure. Spring-tension-based or pressure-based securing mechanisms, such as a clothespin-type clip mechanism, do not allow the skin to breathe, can restrict blood flow and are only recommended for short-term application.
Velcro-based securing mechanisms suffer from the additional drawback that they need a multistep positioning and securing process in order to apply the optical probe to a measurement site. First, the optical probe is placed on the measurement site and then the Velcro strap is secured. In highly agitated environments, such as those associated with newborns, patient transport, exercise testing and ICU care, a multistep process is burdensome and often difficult for the clinician.
Although conventional securing mechanisms are often unworkable in the foregoing environments, the need for non-invasive monitoring in those environments remains. For example, medical practitioners routinely use the Apgar Score to intermittently assess the well being of newborns just after delivery. Two of the typical five components of the Apgar Score, the heart or pulse rate, and degree of oxygenation, e.g., skin color, can readily and accurately be measured continuously using pulse oximetry. In fact, pulse oximetry provides a much more precise monitoring of these foregoing components. For example, pulse oximetry provides a continuous display of the parameters being measured as opposed to the typical Apgar parameters involving clinician auscultation of the chest for a heart rate or the clinician assessment of the coloration of the skin for the blood oxygen saturation.
Based on the foregoing, a need exists for a securing mechanism capable of functioning in environments hostile to adhesive-based, spring-tension-based, and/or hook-and-loop-based securing mechanisms.
Accordingly, one aspect of the instant invention is to provide a securing mechanism for an optical probe capable of functioning in a wide variety of potential environments, including those which are hostile to adhesive-based, spring-tension-based, and/or hook-and-loop-based securing mechanisms. The securing mechanism preferably comprises an elastic sock fitted with an optical probe. According to one embodiment, the sock preferably conforms to a wearer""s foot and comprises at least one toe portion. The at least one toe portion is preferably positioned around the wearer""s great toe or toes, such that the sock maintains a substantially opposing alignment of an emitter and a detector of the optical probe.
According to another embodiment, the sock preferably conforms to a wearer""s hand and comprises at least one finger portion. The at least one finger portion is preferably positioned around one or more of the wearer""s three middle fingers, such that the sock maintains a substantially opposing alignment of an emitter and a detector of the optical probe.
According to another aspect of the invention, the sock may also advantageously be fitted with a manually activated timer circuit, preferably providing an alarm at predetermined intervals, such as those intervals associated with sequencing Apgar scoring.
Therefore, one aspect of the invention includes an optical probe positioner comprising a sock fitted with an optical probe wherein the optical probe measures at least one characteristic of tissue at a measurement site. In addition, the sock comprises an elastomeric material such that the sock substantially conforms to a wearer""s foot or hand, thereby forming a friction fit over a large surface area.
According to another aspect, the invention includes a method of securing an optical probe to tissue at a measurement site in order to determine a characteristic of the tissue. The method comprises propositioning components of an optical probe in a sock such that single motion application of the sock to a measurement site is accomplished by pulling the sock over tissue at the measurement site. In addition, the measurement site is located on a wearer""s foot, toes, hand, finger, or thumb.